Gensets increase hospital emergency power capacity

Located in Columbus, Ga., The Medical Center of Columbus Regional Healthcare System is a 413-bed acute care facility that offers a long list of medical services and provides advanced emergency services as a Level 2 trauma center. The Medical Center is the region’s leading healthcare provider.

The Medical Center relies on emergency generators to ensure uninterrupted electrical power during utility outages. However, The Medical Center’s backup system was an aging collection of gensets that were added as the hospital grew. Some units were more than 30 years old. The gensets could power critical loads during utility outages, but they lacked the capacity to handle the facility’s total electrical load when the HVAC system is included.

The Medical Center has experienced utility power outages lasting from a few seconds to several hours, according to Mark Smith, the hospital’s director of facilities management. The emergency power system supplies electricity to operating rooms, nurseries, and life-sustaining medical devices. These systems also power emergency egress lighting and fire-protection equipment.

Instead of adding to its mix of existing generators, The Medical Center decided to replace them with a new central power plant equipped with four new 2,500 kW generators from MTU Onsite Energy, powered by MTU 20V Series 4000 engines. The engines feature cylinder displacement that provides the reserve horsepower required for load acceptance and precise voltage and frequency control. According to Smith, the new gensets use 30% less fuel than the facility’s old units for a given load.

The gensets generate power at 12,470 V, which is atypical for standby power systems. However, the ability of the generators to operate at this relatively high voltage enables them to match the incoming utility voltage, thereby avoiding energy-wasting transformers between the utility and the central plant. Also, there is less voltage drop across the underground cables that connect the central plant to the hospital across the street.

The new central plant, which houses the four new gensets, is located across the street from the main hospital in a freestanding building. The plant’s layout contributes to the system’s efficiency. For example, the four gensets are arranged so that the exhaust vents from the engines and the cooling air intake vents for the radiators are located on the same side of the building. While care was taken to ensure that the exhaust gases do not reenter the building, the arrangement allows the switchgear to be grouped together along the other side of the building, providing easy maintenance access.

“The new plant has the capacity to power to all electrical loads in the hospital, not just critical life-safety systems,” said Smith. “Among other things, this gives the hospital greater flexibility in managing power use and cost. At any given time, the facility can be totally on the power grid, partially on the grid, or totally off the grid, depending on the situation.”

The Medical Center has provided for several layers of protection against power outages. “If any piece of equipment in this plant fails, there’s a backup piece of equipment that will do its job,” Smith said. “So you’d actually have to have multiple failures before the plant wouldn’t operate.”

The facility’s new central power plant can also be beneficial during extremely hot summer days when power demand soars and utility rates jump. The hospital can run its backup generators to take load off the grid and potentially save electricity costs. According to Smith, during hot weather, the hospital saved approximately $5,000 per day in power costs.

One of the plant’s most impressive features is its 10 MW generating capacity. The Medical Center typically runs on about 4 MW of power. This means the hospital’s power needs could grow by 80%, leaving the remaining generator to be used as a redundant standby unit or to accommodate maintenance or testing.